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Why are bugs so reckless near danger?

  1. Aug 28, 2014 #1
    I'm 21 years old, was in class two days ago... saw a spider under my desk crawling into the aisle. I was bored so before it got far away, I leaned back in my chair, slid my foot into the aisle, and crunched the little guy as inconspicuously as I could.

    I tilted my foot on its side to jokingly show the flattened little guy to my friend sitting across, who sort of snickered when we saw that he was stuck to some mud/grass on my running shoe and half alive. As I was doing this I wondered what motivated the bug to get so close.

    Now, I've been stepping on bugs my whole life. Why crawl next to a giant sneaker unless you were looking to be crushed! Seems hard not to notice that a huge white rubber thing which smashes might be dangerous.. hah.

    Why do bugs act in that way?
  2. jcsd
  3. Aug 28, 2014 #2
    We're not dealing with a lot of brain power here. Is it you expectation that the spider recognizes a sneaker as something more dangerous than a log?
  4. Aug 28, 2014 #3

    jim mcnamara

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    This is an opinion, at work, do not have time to dig out citations.
    (FWIW: spiders are not insects, but that is not to the point :) ).

    Let's do insects. Insects do not see the way mammals do. Many do not even see in the same wavelengths of light (spectrum) that we see. Bees are an example. Cave dwelling species are blind. Insects also sense vibration very well and can detect certain molecules in the air really well, example: pheromones.

    So, a very large number of responses insects have to environmental stimuli are 'hard-wired'. Largely because their brains are not doing a whole lot of input preprocessing of the data. Like us humans do.

    Think of them in human terms as dimwits with super sharp perceptions with limited input bandwidth, but with super fast responses.

    Since a huge part of animal biomass on Earth is insects, this whole strategy has clearly paid off immensely well. It just does not serve individual bugs well in all circumstances.

    The insect's response to stimulus does not involve cognition - thinking about input data, classifying the threat, and then responding. Insects just "do". Shadow moves, jump away. Air from arriving fly swatter (Another shadow) vibrates hairs on the bugs abdomen - fly away. The reason fly swatters have long handles is to increase the speed of the incoming swat to the point the fly cannot get away in time. Many still do.

    Or if you like to think this way: bugs have evolved to cope with the fact they are on the menu for just about all kinds of other animals, including insects. The evolutionary response to being a menu item is called R-selection. Insects lay lots of eggs(like 30000+) and die off in droves before the remaining adults ever get a chance to lay any eggs at all.

    Large mammals like humans, whales, and elephants are the opposite. Called K-selection. Humans have few children (14 is a huge number for us), and most children are not eaten by predators or killed off in other ways before they can reproduce.
  5. Aug 28, 2014 #4
    I've seen flies dart away in the blink of eye. Swatting the little guys can be hard. However some bugs don't really seem to exhibit such caution or reactions.

    The spider crawled right under me. And I've stepped on anthills where the ants don't even run away, even after I've crushed them and their home.
  6. Aug 28, 2014 #5


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    It sounds like you enjoy bringing death and danger to their homes.
  7. Aug 28, 2014 #6


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    Actually humans behave the same way as the bugs. I bet you don't feel scared when you are standing at the side of a road and huge metal objects traveling at 60 mph or more are missing you only by inches.
  8. Aug 28, 2014 #7
    More often than not in my experience, spiders crawl toward me! Like you, I have always been baffled by this. A friend of mine said it's because they're predators, so they automatically obey the predatory instinct without having the intelligence to assess that you're more than they can chew. It made sense, but I don't know if it's true.
  9. Aug 28, 2014 #8

    jim hardy

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    Majority of flies will hide when you get out the swatter.

    Try it......
  10. Aug 28, 2014 #9
    If you see flies in the room just open a window (no screen) and wave your arms frantically. The flies will leave through the window. Please post a video of yourself doing this.

    Best video wins an electronic fly swatter. Do those things work?
  11. Aug 28, 2014 #10


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    That doesn't work very well for me. My conclusion is that flying insects sense the change in light level and/or temperature between inside and outside, and won't cross the "invisible" boundary.

    Flies are quite easy to squash, if you wait for them to settle on something and creep up on them slowly from behind. You can get to within half an inch before they suspect anything at all.
  12. Aug 28, 2014 #11
    There are more extreme cases than that.
    In 1981, five technicians enter the space shuttle Columbia not realizing it was still purged with gaseous N2. Four fell unconscious and three were killed: John Bjornstad, Forrest Cole, and Nick Multon.
    At the time they entered the shuttle, none of them had any indication that there was a threat.
  13. Aug 28, 2014 #12
    Guy seems like a troll.
  14. Aug 28, 2014 #13
    Give the guy a break. He's still only 21.
  15. Aug 29, 2014 #14
  16. Aug 29, 2014 #15
    To me, it sounds more like he enjoys experimenting with the bug's reactions. No need to make him feel guilty about it; there are billions of bugs out there, and he's squashing less than 0.0001% of them.

  17. Aug 30, 2014 #16
    Mostly this. They're just bugs; I don't see it as much different than stepping on tiny robots. Me stepping on an anthill is like stepping on a tiny automated robot factory that will self-repair. Maybe it's destructive, but in the end I'd still just be toying with mindless robots. It doesn't sound to me like "bringing down death and danger" like someone referenced.

    I'm a pretty good guy by most standards. I don't think the way I treat bugs (admittingly, like dirt) has much bearing on that.. If it did, I'd be one of the worst guys out there.
    Last edited by a moderator: Aug 30, 2014
  18. Aug 30, 2014 #17


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  19. Aug 31, 2014 #18
    Cockroaches are smart :grumpy:
  20. Sep 4, 2014 #19
    Good video.. but what does it have to do with this topic?

    Also, why should it matter if cockroaches are smart..
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